Electro-pneumatic controllers (also called electro-pneumatic regulators) are typically used to control the pressure of control fluid used to position a pneumatically-controlled device, such as a regulator. For example, an electro-pneumatic controller can be used to control the pressure of control fluid into a pneumatic actuator of a process control valve or regulator to position the process control valve or regulator. The electro-pneumatic controllers may include one or more passageways to receive the control fluid, and one or more solenoid valves may control the flow of the control fluid through the passageways. The one or more solenoid valves may be in communication with a microprocessor, which may be in communication with one or more sensors disposed outside of the electro-pneumatic controller to control the electro-pneumatic controller and/or the process control valve or regulator. The one or more passageways, one or more solenoid valves, and the microprocessor may all be disposed within a housing that includes a base and a cover.
In some cases, the control fluid may be flammable or explosive in nature. In such cases, the possibility of an internal explosion may be too great to use electro-pneumatic controllers. A need exists for an explosion resistant electro-pneumatic controller.